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Unformatted text preview: SOBJECT 1. Free-Wheeling Operation. 2. Three-phase bridge rectifier. 3. The half-controlled bridge rectifier. The operation of a polyphase ac phase-controlled rectifier with an inductive load is modified when a free-wheeling diode is connected across the load. As in the single-phase circuit, this diode diverts the flow of thyristor current by allowing the load current to circulate through it during parts of the cycle when the output voltage tends to become negative. 1 Three-phase bridge rectifier It is redrawn in Fig.b to emphasize that it may be regarded as two three-phase half-wave circuits connected in series. The upper group has a common cathode connection and operates in usual manner. If ther is no firing delay, the thyristor with the most positive anode conducts and produces a positive output voltage at P relative to the neutral. The lower half-wave group has a common anode connection, and the thyristir with ther most negative cathode conducts to make terminal N negative with respect to the neutral. thyristir with ther most negative cathode conducts to make terminal N negative with respect to the neutral....
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This note was uploaded on 10/05/2011 for the course EECS 101 taught by Professor Hero during the Spring '11 term at National Taipei University.
- Spring '11